1. Field of the Invention
This application relates to an improved form of a hand held printed matter scanning device. More particularly, it relates to such a hand held scanning device and electronic system incorporating the hand held scanning device which is simple enough in construction and low enough in cost to be usable as an input device with personal computers, terminals and similar systems. Most especially, it relates to such a scanning device and system which is capable of scanning an entire line of printed matter simultaneously.
2. Description of the Prior Art
A variety of scanning devices for sensing textual matter and graphics in printed form and converting the sensed information to a set of electrical signals for use in systems are known in the art. For example, one type of prior art device uses the equivalent of a television camera to take a picture of a piece of paper or other substrate containing the information. This approach requires the use of relatively expensive lens systems. Further, even with a miniaturized television camera, a relatively large body is required to house the required system. As a result, such systems are typically of the size of a conventional photocopying machine.
An alternative approach known in the art is to use a line scanner formed in a body of semiconductor material. Such a solid state sensing device reads one line across a page of paper at a time. By moving the paper across this scanning line, it is possible to construct a complete picture of the paper. As currently implemented, there are some problems with this approach. Such devices that are presently commercially available require that the paper be moved across the scanner. Accomplishing this paper movement requires a relatively complicated paper moving mechanism. Furthermore, commercially available semiconductor line scanners have a length of only one inch. As a result, to scan a full page width of 8.5 inches, it is necessary to use lenses or fiber optics to image the wider page at the narrower semiconductor scanner. Both of these approaches introduce extra cost into the scanner. This results in a device that is smaller and somewhat less expensive than the camera model, but still too expensive for widespread use with lower cost data processing systems, such as personal computers, terminals and similar systems.
Examples of scanning devices of the above two general types are disclosed in the following issued U.S. Pat. Nos. 3,541,248, issued Nov. 17, 1970 to Young; 4,314,159, issued Feb. 2, 1982 to Davis; 4,317,137, issued Feb. 23, 1982 to Tompkins; 4,365,274, issued Dec. 21, 1982 to Takenouchi et. al; 4,402,017, issued Aug. 30, 1983 to Takei and 4,432,022, issued Feb. 14, 1984 to Tokumitsu.
Other examples of such scanning devices are disclosed by Tandon, "Hand Operated Scanner", Xerox Disclosure Journal, Vol. 9, No. 2, March/April 1984, pp. 163-164 and Wallace et. al, "Original Document Size Sensor", Xerox Disclosure Journal, Vol. 9, No. 2, March/April 1984, pp. 159-160. One example of such a scanning device is used in the commercially available Dest Turbofont Model 203 optical character recognition document scanners. The state of the art in such scanning devices is summarized in Luther, "Image Processing Update", Recognition Technologies Today, June 1983, pp. 13-15, 36 and Brody, "Machines that Read Move Up a Grade", High Technology, February 1983, pp. 35-40.
While the art pertaining to such image scanning devices and systems is therefore a well developed one, no such device is presently commercially available which is small enough to be truly portable or low cost enough to be widely used at personal computers, individual terminal workstations, and such low cost systems. The commercially available Dest document scanner is presently the lowest in price of such systems, it is comparable in price to a well equipped IBM personal computer, and it is limited to optical character recognition, with no graphics capability. It therefore is too expensive to become a universally used document scanning input device in low cost systems and is limited to text applications.